Vacuum-solvent thermal synthesis of nickel foam-supported CuO-based sensor electrode for good electrochemical detection of nitrite

Given the bad effect of superfluous nitrites on biology/environment, engineering the fast, sensitive, and real-time quantification of nitrites matters to safeguard both the eco-system and human public health. Here, a CuO nanocatalyst self-supported on nickel foam (CuO@NF) was crafted via facilely fusing a vacuum solvent recipe with ambient thermal annealing. Various characterizations show that hollow sea urchin-like CuO structures were arrayed on substrate to feature a 3D porous motif and large specific surface area. Such traits promise the effective local wetting and enrichment of nitrite to augment the nitrate capture/contact capacity, underlying a highly sensitive electrochemical determination of nitrite. Specifically, a wide linear detection range can span 0.5 to 4250 μM, with a stable current response at a concentration as low as 0.5 μM nitrite. The detection limit or sensitivity is approximately 0.0287 mM or 2.402 mAmM−1 cm−2, respectively. This electrode was also successfully applied to detect the nitrite in complex samples like pickled vegetables with satisfactory recovery rates. Our study shows that the self-supported CuO sensor provides an ingenious tactic to build high-efficiency binderless electrodes for the electrochemical sensing applications.